1. Field of the Invention
The invention relates to a motor control apparatus and a motor control method which control a motor by correcting an output of a resolver.
2. Description of the Related Art
In order to continuously rotate a rotor of a motor using a rotating magnetic field, the rotational position of the rotor is detected. The rotational position of the rotor is detected using a resolver fitted to a rotating shaft.
In other words, the resolver detects the rotational position of the rotor which is rotated, and outputs a position signal corresponding to each rotational position of the rotor as an analogue signal. A central processing unit (hereinafter, referred to as CPU) of a computer converts the analogue signal from the resolver to a digital signal. Based on the digital signal obtained by conversion, the CPU generates a drive signal for supplying an alternating electric current for generating the rotating magnetic field to a stator coil (generally composed of a three-phase coil) which is provided at an outer periphery portion of the rotor. Then, the CPU outputs the drive signal to an inverter. Based on the drive signal output from the CPU, the inverter supplies a predetermined alternating electric current to each phase of the stator coil with predetermined timing. Thus, the stator coil generates the rotating magnetic field, and the rotor is rotated by the rotating magnetic field generated by the stator coil.
However, since a deviation of the output of the resolver such as a 0.5th-order deviation and a first-order deviation generally occurs, the rotational angle output from the resolver is not linearly increased with time. Also, a change in the rotational speed of the rotor may be caused, which may cause the deviation of the output of the resolver.
Thus, Japanese Patent Laid-Open Publication No. 2001-165707 discloses a technology in which the deviation of the output of the resolver is corrected using the rotational speed of the rotor.
However, the Japanese Patent Laid-Open Publication No. 2001-165707 does not disclose a motor control using the output of the resolver which is corrected using the rotational speed of the rotor. Therefore, the motor control has not been improved.